Millions of dead fish surfaced in Maryland’s Chesapeake Bay in the U.S., Tuesday, while similar unexplained mass fish deaths occurred across the world in Brazil and New Zealand. On Wednesday, 50 birds were found dead on a street in Sweden. The news come after recents reports of mysterious massive bird and fish deaths days prior in Arkansas and Louisiana.

The Baltimore Sun reports that an estimated 2 million fish were found dead in the Chesapeake Bay, mostly adult spot with some juvenile croakers in the mix, as well. Maryland Department of the Environment spokesperson Dawn Stoltzfus says “cold-water stress” is believed to be the culprit. She told The Sun that similar large winter fish deaths were documented in 1976 and 1980.

ParanaOnline reports that 100 tons of sardines, croaker and catfish have washed up in Brazilian fishing towns since last Thursday. The cause of the deaths is unknown, with an imbalance in the environment, chemical pollution, or accidental release from a fishing boat all suggested by local officials. More…